Outdoor lighting is designed to withstand the elements without exposing the users to potentially lethal electric power. Those skilled in the art must design products that are safe to be used in wet conditions. To that end, one important characteristic is insulating the portions of the lighting fixture that have live electrical power and heat from moisture. Consequently light fixtures that are exposed to precipitation are designed to prevent infiltration by precipitation under a variety of conditions, and to eliminate the potential for water to be collected in the interior near the live electrical conductors.
Frequently, to prevent water from entering the fixture, outdoor light fixture cases are designed to be used so that light is cast downward through an opening or a lens. For example, prior art light cases for outdoor lighting may be hemispherical or oval shaped and have an opening that is usually positioned to cast the lighting fixture's light downward. The material of the case is generally impermeable to the precipitation to prevent water from entering the cavity of the light case, which contains live electrical conductors and a light source which may be hot and susceptible to breakage when exposed to water.
However, outdoor light fixtures may also be positioned to cast light generally upwards, and may also be stored in a variety of positions. Thus, the light case can accumulate water from condensation or sources of precipitation if placed in a position that allows water to accumulate in the case. In fact, because of the inverted bowl shape of many outdoor light fixture cases, they are susceptible to water collection over a range of upward facing positions.
Importantly, outdoor lighting must withstand environmental tests administered by UL in order to obtain certain UL safety certifications. For example, UL recommends the use of draining vents for fixtures that can accumulate moisture as specified by UL1598. Fixtures without adequate drainage that accumulate excessive moisture during UL testing are rejected. Excessive moisture would be defined as moisture that could find its way into the area of the light fixture where the electrical connections are located. As part of qualification, the outdoor light fixture is exposed to a range of simulated environmental conditions to determine if the fixture can meet the requirement of infiltration by moisture. Thus, valves used to drain moisture from the light case must also resist allowing water to impinge during environmental testing.
Drain valves have been used in light fixtures exposed to the elements, such as headlamps for a vehicle, are typically complex structures, such as disclosed in U.S. Pat. No. 6,254,258, designed to vent fluid when the headlamp is on and to prevent fluid from entering when the headlamp is off by forming a vacuum seal. Other prior art light fixture have moisture control systems, such as of the type disclosed in U.S. Pat. No. 6,883,948, which have separate valve elements for intake and exhaust, and may have special diaphragms that are impermeable to moisture, but allow airflow.
However, a simple and cost-effective solution for resisting impingement of water, and draining moisture from an outdoor lighting case is missing from the prior art. What is needed is a valve that allows water to drain when the light fixture is stored or used in a variety of positions that would otherwise allow water to collect in the light case. The same valve must also resist the infiltration of water in other positions under a variety of environmental conditions. What is also needed is a valve that is economical to produce and easy to manufacture.